A Greater dose of Ractopamine Hydrochloride Enhances Feedlot Performance and Impacts Carcass Characteristics of Calf-Fed Holstein Steers

Abstract

The objective was to evaluate the effects of supplementing ractopamine HCl at the rate of 400 mg steer1 daily in the final 28 d of the feeding period on growth performance and carcass characteristics of Holstein steers. Steers (n = 1,498; initial BW = 547 kg) were randomly assigned to pens (10 pens/treatment) and to a treatment: (1) 0 mg∙steer1∙d1 of RH (CON); (2) Ractopamine HCl fed at 400 mg∙steer1∙d1 of RH (RH) for evaluation over a 28 d period. Steers were fed a finishing diet based on steam-flaked corn and alfalfa hay. Dry matter intake decreased, Average Daily Gain (ADG) was increased and improved feed efficiency (P<0.05) was noted in RH steers. Steers supplemented with RH had heavier final Body Weight (BW) and HCW, greater Dressing Percentage (DP) and larger Longissimus Muscle (LM) area (P<0.05). Ractopamine HCl steers had improved yield grades, as evidenced by a greater percentage of yield grade 1 and a decreased percentage of yield grade 3 (P<0.05) carcasses. Steers supplemented RH had a decreased percentage of cattle grading USDA Choice and a greater percent grading USDA Select (P<0.05). These data indicate that 400 mg∙steer1 daily of ractopamine HCl fed to Holstein steers may improve feedlot phase growth performance, DP, HCW and LM area while having minimal impact on USDA quality grade distribution.